As shown in FIG. 1 which a schematic diagram showing a well-known 2D and 3D image switchable display device, a well-known 2D and 3D image switchable display device 10 generally uses a liquid crystal view separator 12 installed in front of the screen of a liquid crystal display 11. For the watching position of a viewer 13, the installation of the liquid crystal view separator 12 in front of the screen of the liquid crystal display 11 is hereinafter referred to as a front installation method.
Further, under the drive of a proper external electrical voltage V, the liquid crystal view separator 12 presents a light transparent state to realize the display of a 2D image or presents a view separated state to realize the display of a 3D image.
Generally, the liquid crystal view separator 12 consists of a liquid crystal lenticular device or a liquid crystal parallax barrier device. As the related technology disclosed herein belongs to the field of liquid crystal lenticular devices, only well-known technologies are described hereinafter aiming at well-known liquid crystal lenticular devices. The methods that have been proposed regarding the foregoing liquid crystal lenticular device are mainly classified into a surface relief method, a polarization activated method and a patterned-electrode method.
FIG. 2 is a schematic diagram showing the components of a surface relief based liquid crystal lenticular device. The structure shown in FIG. 2 is disclosed in U.S. Pat. No. 6,069,650 and may be understood by reference to accompanying drawing FIG. 3.
The surface relief based liquid crystal lenticular device 50 consists of, from the top down, an upper transparent substrate 51, an upper ITO electrode 52, a plano-concave lens array 53, a plurality of liquid crystal molecules 54, a lower ITO electrode 55 and a lower transparent substrate 56. The plano-concave lens array 53 has an optical reflective index nP; the plurality of liquid crystal molecules 54 made from a nematic liquid crystal material and having characteristics of birefringent optics has an ordinary refractive index no and an extraordinary refractive index ne, wherein no=nP and ne>nP. The upper and the lower ITO electrode layers 52 and 55 are individually configured by alignment layers, a well-known component disposed in liquid crystal devices, and connected with a power supply V.
Further, the liquid crystal lenticular device 50 is installed in front of a liquid crystal screen 60 which is capable of displaying a 2D or 3D image (not shown) on the color filter (CF) 61 thereof, the light source of the 2D or 3D image, after being processed by the outmost polarizer 62 of the liquid crystal screen 60, becomes a linear polarized light source 63 having the polarization direction which is vertical to the surface of accompanying drawing FIG. 2.
In the absence of an external electric field, that is, when V=OFF, the orientation of the nematic liquid crystal molecules is featured in that the optical axis of the nematic liquid crystal molecules is vertically aligned to the surface of accompanying drawing FIG. 2. The extraordinary optical reflective index ne of the liquid crystal molecule is effective when the incident light 63, having a light polarization direction being parallel to the optical axis of the liquid crystal molecule, penetrates the plurality of liquid crystal molecules 54. Further, when the incident light 63 penetrates the plano-concave lens array 53, as ne>nP, the incident light 63 subjects to the effect of a convex lens, consequentially, the foregoing optical characteristic is suitable for presenting a 3D image.
Additionally, in the presence of an external electric field, that is, when V=ON, the orientation of the nematic liquid crystal molecules is featured in that the optical axis of the nematic liquid crystal molecules lies flatly on the surface of accompanying drawing FIG. 2 and is vertically aligned to the upper and the lower ITO electrode layers 52 and 55, that is, parallel to the direction of the electric field (not shown). The ordinary optical reflective index no of the liquid crystal molecule is effective when the incident light 63, having a light polarization direction being vertical to the optical axis of the liquid crystal molecule, penetrates the plurality of liquid crystal molecules 54. Further, when the incident light 63 penetrates the plano-concave lens array 53, as no=nP, the incident light 63 directly penetrates the plano-concave lens array 53 without being deflected by the plano-concave lens array 53, therefore, the foregoing optical characteristic is suitable for presenting a 2D image.
To sum up, the orientation of the liquid crystal molecules of the liquid crystal lenticular device 50 featured in an electric field modulated refractive index is aligned under the control of an external voltage to change the reflective index of the liquid crystal molecules, so as to provide an effect of light penetration or an effect of a lens for linear polarized incident light, so as to finally achieve the purpose of switching between the display of 2D image and 3D image.
FIG. 3 is a schematic diagram showing the components of a polarization activation based liquid crystal lenticular device. The structure shown in FIG. 3 is disclosed in U.S. Pat. No. 7,058,252 B2 and may be understood by reference to accompanying drawing FIG. 32a. Further, a more detailed description and drawings may be obtained by reference to the description on accompanying drawing FIG. 6 of U.S. Pat. No. 8,279,363 B2.
The polarization activation based liquid crystal lenticular device 190 consists of an electrode substrate component 180, two transparent electrodes 178, a 90-degree rotatable polarizing component 176, a microlens counter substrate 142, a birefringent microlenses 138, an isotropic material 134 and a lens substrate component 132. Further, the other structure shown in FIG. 3 is a well-known liquid crystal display 200 consisting of a backlight source 60, a polarizing component 64, an LCD substrate 66, an LCD pixel component 67, an LCD substrate 80 and a polarizing component 184.
The two transparent electrodes 178 individually installed on the electrode substrate component 180 and the microlens counter substrate 142 constitute an electrically switchable polarizer 191 with the 90-degree rotatable polarizing component 176; and by driving the two transparent electrodes 178 using a proper external voltage (not shown), the 90-degree rotatable polarizing component 176 may rotate the polarization direction of the linear polarized incident light by 90 degrees or maintains the polarization direction of the linear polarized incident light. Further, the birefringent lens 138, which is a structure provided with a liquid crystal lenticular device, is made from a birefringent material having an ordinary refractive index no and an extraordinary refractive index ne, wherein the ordinary refractive index no is equal to the optical refractive index n1 of the isotropic material 134, that is, n1=no.
When a 2D image is displayed, the image light source (not shown) output from the polarizing component 184 has characteristics of linearly polarized light and enters the electrically switchable polarizer 191 which, for the incident light, maintains the polarization direction of the incident light so that the polarization direction of the incident light is vertical to the direction of the optical axis of the birefringent lens 138, thus, the incident light penetrates the birefringent lens 138 having an ordinary optical reflective index no. As the optical refractive index n1 of the isotropic material 134 is equal to no, the birefringent lens 138 loses its efficacy as a lens.
When a 3D image is displayed, the image light source (not shown) output from the polarizing component 184 has characteristics of linearly polarized light and enters the electrically switchable polarizer 191 which, for the incident light, rotates the polarization direction of the incident light by 90 degrees so that the polarization direction of the incident light is parallel to the direction of the optical axis of the birefringent lens 138, thus, the incident light penetrates the birefringent lens 138 having an extraordinary optical reflective index ne. As the optical refractive index n1 of the isotropic material 134 is not equal to ne, the birefringent lens 138 has the function of a lens.
FIG. 4 is a schematic diagram showing the components of a patterned-electrode based liquid crystal lenticular device. The structure shown in FIG. 4 is disclosed in U.S. Pat. No. 8,330,881 B2 and may be understood by reference to accompanying drawing FIG. 12a. 
The patterned-electrode based liquid crystal lenticular device 100 consists of a liquid crystal material 90, an ITO lens electrode layer 92, an ITO common electrode layer 94 and two glass substrates 96 and 98.
The ITO lens electrode layer 92 which consists of a plurality of single electrodes of a proper width that are spaced from each other by a proper distance is connected with an external electronic circuit (not shown) capable of providing all the single electrodes with a proper periodically distributed drive voltage to generate a periodically distributed quadratic electric field, so as to arrange the liquid crystal molecules of the liquid crystal material 90 into a plurality of gradient index lenses (GRIN Lens) gradually changed in optical reflective index.
That is, the external electronic circuit provides a suitable voltage for the pair of single electrodes 99 shown in FIG. 4 and the electrodes located between the pair of the single electrodes 99 to generate the foregoing quadratic electric field distribution for gradually reversing the alignment direction of the liquid crystal molecules between the two electrodes 99 into a 180 degree to finally form a gradient index structure. In this way, the patterned-electrode based liquid crystal lenticular device 100 has the function of a lens and realizes the purpose of presenting a 3D image.
Further, in the case of the display of a 2D image, the external electric circuit is disabled in voltage supply so that all the liquid crystal molecules are arranged in the same vertical direction to form a transparent element not having the function of a lens. Further, the ITO common electrode layer 94 consisting of continuously distributed electrodes is also connected with the external electronic circuit to form an electrical common layer.
In conclusion, the feature of three kinds of liquid crystal lenticular devices is to use liquid crystal molecules, so as to achieve the modulation of optical index. Thus, the foregoing three well-known technologies are classified into the technical field of liquid crystal dependent liquid crystal lenticular devices.